Method of manufacturing light emitting device

ABSTRACT

To make a light emitting device, a light emitting element is placed in a recess of a package, powders having a fluorescent material and coated with inorganic particles are provided, the fluorescent powders, fillers and a resin are mixed, the light emitting element placed in the recess of the package is sealed with the resin, and a centrifugal force is applied to the sealed package so that the fluorescent powders and the fillers sediment are pushed toward a bottom of the recess.

This application claims priority from Japanese Patent Application No.2010-248343 filed on Nov. 5, 2010, the content of which is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting device using a lightemitting element and a method of manufacturing the light emittingdevice, particularly to a light emitting device in which a lightemitting element is sealed with a resin, and to a method ofmanufacturing the light emitting device.

2. Description of Related Art

A light emitting device using a light emitting element is small in sizeand has a low power consumption with long service life, and is used in awide variety of applications such as backlight for liquid crystaldisplays and in-car devices. Typically, the light emitting element issealed with a resin when it is incorporated in a light emitting devicefor protection of a wire-bonded portion and other wiring portions, andfor protection of the light emitting element itself.

Light emitted from the light emitting element is a single-color lightsuch as red, green, or blue, and a fluorescent material for convertingit to light having a different wavelength may be used in combinationwith the light emitting element. For example, a light emitting device isknown, which is capable of emitting white light by additive mixing ofcolors of the light emitted from an LED exiting directly to the outsideand the wavelength-converted light emitted from the light emittingelement.

Conventionally, a light emitting device having a light emitting elementsealed with a resin which contains a fluorescent material is disclosedfor example in JP 2005-277331A, in which the density of the fluorescentmaterial in the resin and the viscosity of the uncured resin areadjusted to minimize deposition of the fluorescent material and toprevent the fluorescent material from covering the surface of the lightemitting element.

With this, a decrease in the light extraction efficiency of the lightemitting element and loss in propagation of light caused by thefluorescent material are suppressed and thus improvement in the emissionintensity of the light emitting device are obtained.

Also, a semiconductor light emitting device having a light emittingelement sealed in a resin package is disclosed for example in JP2000-164937A in which the resin package has a two-layer structure of asealing resin layer and a fluorescent material layer containing afluorescent material for converting the emission wavelength, where thetwo layers include a resin as a common material, and the fluorescentmaterial for converting color of light is arranged in the vicinity ofthe light emitting element.

This arrangement suppresses occurrence of detachment at the interfacebetween the resin layers and an optical warpage due to encapsulationwith a plurality of resin layers, and to reduce exposure of thefluorescent substance near the surface of the resin layer to externallight so that emission caused by an excitation of the fluorescentsubstance by external light can be prevented.

However, in such a light emitting device described in JP 2005-277331A,the fluorescent substance is dispersed in a resin, so that light fromthe light emitting element hits the fluorescent substance dispersed inthe resin multiple times and attenuates. Also, a difference occurs inthe amount of resin used to seal the light emitting element by way ofpotting or printing, resulting in difference in the amount of thefluorescent substance included in each of the light emitting devices.Accordingly, the difference in the amount of light increases between thelight from the light emitting element and the wavelength-converted lightfrom the fluorescent substance which absorbed the light from the lightemitting element. In such a semiconductor light emitting devicedescribed in JP 2000-164937A, the fluorescent substance is over-packedin the vicinity of the light emitting layer of the light emittingelement, which makes it difficult to extract light from the lightemitting element to outside and may result in color unevenness.

SUMMARY OF THE INVENTION

The invention provides a method of manufacturing a light emittingdevice. The method includes placing a light emitting element in a recessof a package, providing powders comprising a fluorescent material andcoated with inorganic particles, mixing the fluorescent powders, fillersand a resin, sealing the light emitting element placed in the recess ofthe package with the resin having the fluorescent powders and thefillers mixed therein, and applying a centrifugal force to the sealedpackage so that the fluorescent powders and the fillers are pushedtoward a bottom of the recess.

The invention also provides a light emitting device that includes apackage having a recess, a light emitting element including a lightemitting layer and disposed in the recess, a first lower layer havingfluorescent particles and disposed on a bottom of the recess, a secondlower layer having the fluorescent particles and disposed on a top ofthe light emitting element, and a first upper layer having fillers anddisposed on the first lower layer. The first upper layer covers a sideedge of the light emitting layer. The device also includes a secondupper layer having the fillers and disposed on the second lower layer,and a resin sealing the light emitting element, the first and secondlower layers and the first and second upper layers in the recess.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a light emitting elementaccording to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a light emitting elementaccording to a second embodiment of the present invention.

FIGS. 3(A) to 3(C) are schematic views illustrating a step of a methodof manufacturing according to the present invention.

FIG. 4 is a schematic cross-sectional view illustrating a step of amethod of manufacturing according to the present invention.

FIG. 5 is a schematic cross-sectional view illustrating a step of amethod of manufacturing according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings. The preferred embodimentsare intended as illustrative of a light emitting device and a method ofmanufacturing the light emitting device to give a concrete form totechnical ideas of the present invention, and the scope of the inventionis not limited to those described below.

The sizes, materials, shapes and the relative configuration etc. of themembers described in embodiments are given as an example and not as alimitation to the scope of the invention unless specifically describedotherwise. The sizes and the arrangement relationships of the members ineach of drawings are occasionally shown exaggerated for ease ofexplanation. In the description below, the same designations or the samereference numerals denote the same or like members and duplicativedescriptions will be appropriately omitted. In addition, a plurality ofstructural elements of the present invention may be configured as asingle part which serves the purpose of a plurality of elements, on theother hand, a single structural element may be configured as a pluralityof parts which serve the purpose of a single element.

A first embodiment of the present invention will be described in detailbelow with reference to accompanying drawings. FIG. 1 is a schematiccross-sectional view of a light emitting element according to a firstembodiment of the present invention. FIGS. 3(A) to 3(C) are schematicviews illustrating a step of a method of manufacturing according to thepresent invention, showing fluorescent material having inorganicparticles on the respective surfaces.

A light emitting device according to a first embodiment includes apackage 10, a light emitting element 11 having a light emitting layer12, a resin 13, a deposited layer of fluorescent material 14, adeposited layer of filler 15, and wires 16. The light emitting element11 having the light emitting layer 12 is disposed in a face-up manner onthe bottom surface of the recess defined in the package 10, and a pairof positive and negative electrodes (not shown) of the light emittingelement 11 are connected to the corresponding lead electrodes (notshown) respectively fixed to the package by a bonding wire 16. The lightemitting element 11 fixed on the bottom surface of the recess defined inthe package 10 is sealed with the light transmissive resin 13.

The deposited layer of fluorescent material 14 is disposed on the uppersurface of the light emitting element 11 and on the bottom surface ofthe recess defined in the package 10 so as to be lower than the lightemitting layer 12 so that the light emitting layer 12 is exposed fromthe deposited layer of fluorescent material 14 at the side surfaces ofthe light emitting element 11. The deposited layer of filler 15 isfurther disposed at least on the upper surface of each portion of thedeposited layer of fluorescent material 14. It is sufficient that thelight emitting layer 12 is at least exposed from the deposited layer offluorescent material 14 and may be covered with the deposited layer offiller 15. It is preferable to cover the light emitting layer 12 withthe deposited layer of filler 15 so that the light emitted from thelight emitting layer 11 in a side direction of the light emittingelement 11 and the light emitted from the light emitting layer 12 andwavelength converted at the deposited layer of fluorescent material 14at the bottom surface of the recess defined in the package 10 can bediffused while passing through the deposited layer of filler 15, whichcontributes further mixing the colors of light.

The deposited layer of fluorescent material 14 is a deposit of thefluorescent material 20 having inorganic particles 22 on its surface,and has a thickness of 20 to 150 μm. In the present embodiment of theinvention, the term “having inorganic particles 22 on its surface” meansthat the inorganic particles 22 are fine particles with diameters muchsmaller than the fluorescent material particles 21 and are adhered(coated) on the surfaces of the fluorescent material particles 21, insuch a manner that, the inorganic particles 22 are aggregated to coverthe entire surface of a fluorescent material particle 21 or to adhere tothe surface of a fluorescent material particle exposing a part of thesurface of the fluorescent material particle 21.

A light diffusing agent may be contained in the resin 13. In such case,the light diffusing agent is not deposited but is dispersed in the resin13. If a fluorescent material is provided around the light emittinglayer 12, a large portion of light emitted from the light emitting layer12 will be subjected to wavelength conversion, so that the color oflight emitted from the light emitting device tends to be stronglyaffected by the wavelength-converted light.

The light emitting device according to the first embodiment of thepresent invention includes a light emitting element 11 having a lightemitting layer 12 exposed from the deposited layer of fluorescentmaterial 14, so that the directions of the light emitted from the lightemitting element 11 are in a direction to the outside of the lightemitting device 100, in a direction toward the upper surface of thelight emitting layer 12 passing through the deposited layer offluorescent material 14 where the wavelength of the light is convertedby the fluorescent material 20 having inorganic particles 22 on itssurface and to the outside of the light emitting device 100, and in adirection in which the light from the light emitting layer 12 propagatesto the deposited layer of fluorescent material 14 which is lower thanthe light emitting layer 12, where the wavelength of the light isconverted by or reflected at the fluorescent material 20 havinginorganic particles 22 on its surface, and is emitted outside of thelight emitting device 100.

With this arrangement, the light emitted from the light emitting layer12 can be prevented from being excessively wavelength-converted by thefluorescent material, so that the influence of the color ofwavelength-converted light can be suppressed and the state of mixingcolors of light can be improved. Also, dependency to the amount (height)of the sealing resin, which is a concern in the case where a fluorescentmaterial is dispersed in a resin, can be reduced, and thus unevenness inthe color hue can be suppressed.

Next, a light emitting device according to the second embodiment will bedescribed. FIG. 2 is a schematic view of a light emitting elementaccording to the second embodiment of the present invention. The lightemitting device according to the second embodiment is substantially thesame as that of the first embodiment, except that the light emittingelement 41 is disposed on the submount 31.

It is sufficient that the submount 31 has an upper surface capable ofarranging the light emitting element 41 thereon and is preferable thatthe surface area of the upper surface is larger than the surface area ofthe bottom surface of the light emitting element 41. In the case wherethe surface area of the upper surface of the submount 31 is larger thanthe surface area of the bottom surface of the light emitting element 41,the deposited layer of fluorescent material 44 and the deposited layerof filler 45 are also provided at a portion of the submount 31 exposedfrom the light emitting element 41 when viewed from the top.

The deposited layer of fluorescent material 44 is such that a partthereof provided on the upper surface of the sumbount 31 has a smallersurface area and is closer to the light emitting layer 42 than a partthereof provided on the bottom surface defining the recess in thepackage 40. Therefore, the wavelength of the light from the lightemitting layer 42 is facilitated to be converted at the deposited layerof fluorescent material 44 at the upper surface of the submount 31,thus, the amount of wavelength-converted light can be further reduced.Also, the efficiency of the heat dissipation of the light emittingelement 41 can be improved by the submount 31.

The light emitting device according to the third embodiment may have afluorescent material 20 having inorganic particles 22 on its surface,where the surfaces of the fluorescent material particles 21 are coveredwith a substantially flat film of a covering material made of adifferent material than the fluorescent material 21, and are furthercoated with fine inorganic particles 22. Other arrangements aresubstantially the same as that in the first or second embodiments.

With this arrangement, the fluorescent material particles 21 having lowresistance against moisture and a gas can be protected by the coatingmaterial, and dispersion of the fluorescent material 20 having inorganicparticles 22 on its surfaces in the uncured resin can be improved by theinorganic particles 22. Each component of the present embodiment will bedescribed in detail below.

The light emitting element is, for example, a semiconductor lightemitting element such as a light emitting diode, and any of those usedin the art can also be used. The emission peak of the light emittingelement is set to, for example, at 460 nm when the light emittingelement is used in combination with a YAG-based fluorescent materialwhich will be described later. The light emitting device 100 shown inFIG. 1 exemplifies a light emitting element having positive and negativeelectrodes on its upper surface, but a light emitting element mounted inflip-chip manner or a light emitting element in which GaN is attached ona Si substrate and the electrodes are disposed respectively on thecorresponding sides of the light emitting element can also be used.According to the purpose and application, the composition, the color ofemitting light, the size and the number of light emitting element to beemployed can be selected appropriately.

The package is provided with a recess defined by a bottom surfacecapable of mounting a light emitting element thereon. Two leadelectrodes (not shown) which are spaced apart from each other areprovided on the bottom surface of the recess (a part of the uppersurface of the package), and respectively connected to a correspondingexternal connect terminal. On the bottom surface of the recess providedin the package, a mount for disposing the light emitting element thereonmay be formed integrally with the package or a submount or a pedestalmay be attached.

The inorganic particles are provided as a coating, to cover the entiresurface of the fluorescent particles or to attach to the surface of thefluorescent particles exposing a part of the surfaces of the fluorescentparticles. Particularly, the effect is excreted with the fluorescentmaterial where the coating is provided evenly on the entire surfaces ofthe fluorescent material particles, in either the case where theinorganic particles cover the entire surfaces of the fluorescentmaterial particles or where the inorganic particles cover the surfacesof the fluorescent material particles so that a part of the surfaces ofthe fluorescent material particles are exposed among the inorganicparticles. It is preferable that the coating is applied evenly on thesurfaces of the fluorescent material particles, and the state of thecoating can either be a thin film or aggregations of fine particles eachhaving a diameter of 1 to 10 nm, as long as the coating is substantiallyuniform. For the material of the inorganic particles, a metal oxide or ametal nitride is preferable. Examples of such a metal element includeAl, Si, or In, Ga or a rare earth element, and with using one orplurality of such elements, a suitable coating can be obtained. Thecoating may be applied in a plurality of layers, for example, applying acoating of a compound including phosphorus such as a phosphate on thesurfaces of the fluorescent material particles and then further applyinga coating of inorganic particles thereon.

The fluorescent material particles are coated with inorganic particlesand are excited by light from the light emitting element and emit lighthaving wavelength different than that of the excitation light. Examplesof the fluorescent material include: (a) a rare-earth aluminatefluorescent material activated mainly with a lanthanoid element such asCe, and (b) a YAG-based fluorescent material represented bycompositional formula such as Y₃Al₅O₁₂:Ce, (Y_(0.8)Gd_(0.2))₃Al₅O₁₂:Ce,Y₃(Al_(0.8)Ga_(0.2))₅O₁₂:Ce, or (Y,Gd)₃(Al,Ga)₅O₁₂. Fluorescent materialparticles other than those described above, having similar properties,performance, and effects can also be used. Two or more kinds offluorescent materials having different specific gravity can be usedalso. The fluorescent material particles preferably have a specificgravity greater than that of the filler in the deposited layer offiller. Fluorescent material particles and filler having different sizemay be used, and with mixing them, a further densely packed depositedlayer can be obtained.

A resin is a member for sealing a light emitting element, and accordingto the aim and application, a silicone-based resin such as aphenyl-based silicone resin, a dimethyl-based silicon resin, or a rigidhybrid silicone resin, or an epoxy-based resin can be used.

Fluorescent material particles, fluorescent material having inorganicparticles on their surfaces, a filler, a diffusion agent, or the likemay be contained in the resin.

The deposited layer of fluorescent material is a deposit formed in sucha way that after sealing a light emitting element which is disposed to apackage defining a recess with a resin containing a fluorescent materialhaving inorganic particles on its surface, the package is centrifugallyrotated so that the fluorescent material which is contained in the resinand which has inorganic particles on its surface is deposited at thelight emitting element side. The resin may be contained in the depositedlayer of fluorescent material. The deposited layer of fluorescentmaterial is substantially flat with respect to the bottom surface of thepackage where the light emitting element is disposed.

The deposited layer of filler is a deposit formed in such a way thatafter sealing a light emitting element which is disposed to a packagedefining a recess with a resin containing a filler, the package iscentrifugally rotated so that the filler which is contained in the resinis deposited at the light emitting element side. The resin may becontained in the deposited layer of filler. The filler contained in theresin contributes to facilitate adjustment of the viscosity of uncuredresin before cure, or adjustment of the hardness and the linearexpansion coefficient of the cured resin. The filler preferably has aspecific gravity smaller than the fluorescent material having inorganicparticles on its surface and forming the deposited layer of fluorescentmaterial. The deposited layer of filler is disposed covering the uppersurface of the deposited layer of fluorescent material. Also, the filleris deposited covering the entire portion or at least a part of thebonding wires which connect the positive and negative electrodes (notshown) of the light emitting element and the respective metal leadelectrodes (not shown) fixed to the package. With the deposited layer offiller, light from the light emitting element (including the wavelengthconverted light by the fluorescent material having inorganic particleson the surface thereof) can be reflected to improve the light extractionefficiency, and disconnection of wire can be suppressed.

For the filler, silicone dioxide is preferably used for reducing thelinear expansion coefficient of the resin, but a white pigment such asalumina, titanium oxide, or barium sulfate may also be used. In order toimprove the contrast, a black pigment such as carbon can be employed toan amount so as not to impede propagation of light. Such pigments may beused singly or as combination of two or more thereof. The particlediameter and/or concentration of each member, the mixing ratio of themembers, or the like can be appropriately selected.

A method of manufacturing a light emitting device according to thepresent invention will be described below. In addition to those processsteps described below, well-know processes may be applicable in makingthe light emitting device of this invention. FIG. 1 is a schematiccross-sectional view of a light emitting element according to a firstembodiment and FIG. 2 is a schematic cross-sectional view of a lightemitting element according to a second embodiment. FIGS. 3 to 5 areschematic diagrams each showing a step of a method of manufacturingaccording to the present invention.

In the method of manufacturing a light emitting device according to thepresent invention, inorganic particles are provided on the surfaces offluorescent material particles which tend to aggregate so thatoccurrence of aggregation of the fluorescent material particles can beavoided and a narrow distribution of the particle diameter can beobtained, and that dispersion of the fluorescent material particles,which have inorganic particles on their surface, in an uncured resin canbe improved. With this arrangement, in a step of centrifugalsedimentation, the fluorescent material particles having inorganicparticles on their surfaces are facilitated to precipitate evenly andcan deposit to form substantially uniform flat surface. Further, theaverage particle diameter and the specific gravity of the fluorescentmaterial particles having inorganic particles on their surfaces and ofthe filler are respectively arranged, so that, using a centrifugalsedimentation technique, the fluorescent material particles havinginorganic particles on their surfaces are precipitated faster than thefiller particles.

The method of manufacturing a light emitting device of the presentinvention includes a step of mounting a light emitting element 11, astep of preparing a fluorescent material 20, a step of centrifugalsedimentation, and a step of curing resin.

The light emitting element 11 is dye-bonded on the bottom surface of arecess defined in a package 10, then using wires 16, the positive andnegative electrodes (not shown) of the light emitting element 11 areconnected respectively to the corresponding electrodes (not shown)provided to the package 10.

The light emitting element 11 can be dye-bonded directly on the bottomsurface defining the recess in the package 10, or alternatively canarranged on a submount or a pedestal provided on the bottom surfacedefining the recess in the package 10.

Inorganic particles 22 are applied on the fluorescent material particles21 to obtain the fluorescent material 20 having inorganic particlesthereon. Examples of the method of coating include a method employing achemical vapor reaction, a method of using a vapor-phase raw material,and a method of using a liquid-phase raw material. Also, a sol-gelmethod to obtain a coating of silicone oxide by hydrolysis of ethylsilicate may be employed.

Other coating methods can be employed, such as a method in which asource material of metal element, a coreaction material, and thefluorescent material particles are stirred in a solution so as to adherea target coating substance on the surfaces of the fluorescent materialparticles, or a method in which an intermediate member is adhered on thesurfaces of the fluorescent material particles and then fired in anitrogen atmosphere to obtain a desired coating. In this specification,the term “coreaction material” refers to a material capable of reactingwith the source material of the metal element to form the desiredcoating.

Examples of other coating methods includes a method in which very smallparticles of a substance used as a coating material (inorganicparticles) and fluorescent material particles are stirred at high speedso as to electrostatiscally adhere the very small particles of thecoating material on the surfaces of the fluorescent material particlesor a method in which adhesion due to a difference in surface potential,for example, the fluorescent material particles 21 (+) and the inorganicparticles 22 (−) before coating, is used for coating. The electrostaticrepulsion between the particles due to the surface potential of theinorganic particles 22 improves dispersibility of the fluorescentmaterial particles 20, which have the inorganic particles 22 on thesurfaces thereof, in the resin 30. The coating may be applied in aplurality of layers using one or more method described above.

After the mounting step of the light emitting element 11 and thepreparation step of the fluorescent material 20, the fluorescentmaterial having inorganic particles on the surface thereof and thefiller are mixed into the uncured resin which is in a fluid state, anddispersed to obtain the resin member 30. A diffusing agent may furtherbe contained in the resin 30. The resin 30 is filled in the package 10by way of potting or printing to seal the light emitting element 11. Theresin 30 later takes forms of the transparent resin 13, the depositedlayer of fluorescent material 14, and the deposited layer of filler 15,each of which has light transmissive property.

The fluorescent material 20 having inorganic particles 22 on the surfacethereof and the filler are centrifugally sedimented after filling theresin 30 in the package 10 to seal the light emitting element 11 andbefore curing the resin 30. In the step of centrifugally sedimenting thefluorescent material, the direction of the sum of centrifugal force andgravity is maintained substantially perpendicular to the upper surfaceof the light emitting element. The fluorescent material 20 havinginorganic particles 22 on the surface thereof and the filler areuniformly dispersed in the resin 30, so that with maintaining thedirection of the force acting on the light emitting device 100 in adirection of the upper surface to the lower surface of the lightemitting device 100, deposition of a continuous layer which is closelypacked and has a uniform thickness can be obtained. The fluorescentmaterial 20 having inorganic particles 22 on the surface thereof isdeposited on the upper surface of the light emitting element 11 andbeneath the light emitting layer 12 of the light emitting element 11 toform the deposited layer of fluorescent material 14 and the depositedlayer of filler 15 is formed to cover at least the upper surface of thedeposited layer of fluorescent material 14.

The thickness of the deposited layer of fluorescent material 14 and thedeposited layer of filler 15 can be adjusted respectively to a desiredvalue by adjusting the amount and the particle diameters of thefluorescent material 20 having inorganic particles on the surfacethereof and that of the filler.

In the case where a diffusion agent is contained in the resin 30, thediffusion agent is not sedimented in the step of centrifugalsedimentation described above and stays dispersed in the resin 13.

After forming the deposited layer of fluorescent material 14 and thedeposited layer of filler 15, the resin 13, the deposited layer offluorescent material 14, and the deposited layer of filler 15 arehardened to obtain the light emitting device 100 or 200.

Example 1

The light emitting device according to Example 1 will be described withreference to FIG. 1. FIG. 1 is a schematic cross-sectional view of alight emitting device according to the first embodiment of the presentinvention, and the light emitting device 100 was fabricated as describedbelow.

The light emitting device 100 according to Example 1 includes a package10, a light emitting element 11 having a light emitting layer 12, aresin 13, a deposited layer of fluorescent material 14, a depositedlayer of filler 15, and wires 16. The resin 13, the fluorescent materialparticles 21, the inorganic particles 22, and the filler used in Example1 were as follows.

(1) Resin 13

Type: Phenyl-containing silicone resin

Viscosity: 200 to 20000 mPa·s

(2) Fluorescent Material Particle 21

Composition: Y₃Al₅O₁₂:Ce

Specific Gravity: 4.6

Average Diameter: 10.5 μm

Median Particle Diameter: 12.5 μm

(3) Inorganic Particle 22

Type: Colloidal Silica (SiO₂)

Average Particle Diameter: 10 to 20 nm

(4) Filler

Composition: SiO₂

Specific Gravity: 2.2

Average Diameter: 6.8 μm

In Example 1, first, a light emitting element 11 was mounted on thebottom surface of the recess which was defined in the package 10 andwhich was provided with lead electrodes (not shown). Then the positiveand negative electrodes (not shown) disposed on the upper surface of thelight emitting element 11 were respectively connected to the leadelectrodes through the wires 16.

Meanwhile, making use of respective surface potentials, the inorganicparticles 22 are coated on the fluorescent material particles 21 toobtain the fluorescent material 20 having inorganic particles thereon.

The fluorescent material 20 having the inorganic particles 22 on thesurface thereof and the filler were mixed in the uncured resin which wasin a fluid state and were dispersed to obtain the resin member 30. Theresin member 30 was filled in the package 10 to seal the light emittingelement 11.

Then, without hardening the resin member 30, the fluorescent material 20having the inorganic particles 22 on the surface thereof and the fillerwere sedimented by applying a centrifugal force. The fluorescentmaterial 20 having inorganic particles 22 on the surface thereof wasdeposited on the upper surface of the light emitting element 11 andbelow the light emitting layer 12 and the filler was deposited on theupper surface of the fluorescent material 20 having inorganic particles22 on the surface thereof. Thus, the deposited layer of fluorescentmaterial 14 and the deposited layer of filler 15 were formed.

Finally, the resin member was hardened under a condition of at 50° C.for 12 hours, then the temperature was rised to 50° C. to 150° C. in 2hours, and at 150° C. for 4 hours. Thus the light emitting device 100was obtained.

The light emitting device 100 according to Example 1 was fabricated asdescribed above, and thus, the light emitting device 100 capable ofsuppressing occurrence of unevenness of color and of improving the colorproperties in light distribution can be obtained.

Light emitting device according to the present invention can be suitablyemployed for a light source for lighting, an LED display, backlightsource for a liquid crystal display device, signals, a lighted switch,various sensors, various indicators, or the like.

1. A method of manufacturing a light emitting device, comprising:placing a light emitting element in a recess of a package; providingpowders comprising a fluorescent material and coated with inorganicparticles; mixing the fluorescent powders, fillers and a resin; sealingthe light emitting element placed in the recess of the package with theresin having the fluorescent powders and the fillers mixed therein; andapplying a centrifugal force to the sealed package so that thefluorescent powders and the fillers are pushed toward a bottom of therecess.
 2. The method of claim 1, wherein, during the application of thecentrifugal force, a sum of the centrifugal force and gravity has adirection perpendicular to a top surface of the light emitting element.3. The method of claim 1, further comprising mixing the resin and adiffusing agent having the same specific gravity as the resin.
 4. Amethod of manufacturing a light emitting device, comprising: placing alight emitting element in a recess of a package; providing powderscomprising a fluorescent material and coated with inorganic particles;providing fillers having a specific gravity smaller than the fluorescentmaterial and a resin having a specific gravity smaller than the fillers;mixing the fluorescent powders, the fillers and the resin; sealing thelight emitting element placed in the recess of the package with theresin having the fluorescent powders and the fillers mixed therein; andapplying a centrifugal force to the sealed package so as to form alayered-stack on a bottom of the recess and a top of the light emittingelement, the layered-stack comprising a lower layer primarily made ofthe fluorescent powders and in contact with the bottom and the top andan upper layer primarily made of the fillers and disposed on the lowerlayer.
 5. A light emitting device comprising: a package having a recess;a light emitting element comprising a light emitting layer and disposedin the recess; a first lower layer comprising fluorescent particles anddisposed on a bottom of the recess; a second lower layer comprising thefluorescent particles and disposed on a top of the light emittingelement; a first upper layer comprising fillers and disposed on thefirst lower layer, the first upper layer covering a side edge of thelight emitting layer; a second upper layer comprising the fillers anddisposed on the second lower layer; and a resin sealing the lightemitting element, the first and second lower layers and the first andsecond upper layers in the recess.
 6. The light emitting device of claim5, further comprising inorganic particles disposed on surfaces of thefluorescent particles.
 7. The light emitting device of claim 5, whereinthe bottom of the recess is partially raised by placing a submount onthe bottom, the light emitting element is disposed on the submount, andpart of the first lower layer and part of the first upper layer aredisposed on the submount so that the first upper layer covers the sideedge of the light emitting layer.